Consumer purchase of optical discs that contain audio, video, software, or data has generated a multi-billion-dollar industry. Recently, the advent of low-cost optical recording media and drives has enabled widespread unauthorized copy of this content. To defeat this, various copy protection schemes have been proposed. However, some of those schemes rely on characteristics of the digital data stream, which can be copied by sophisticated low-cost recorders using bit-for-bit copying. Other schemes rely on changing the characteristics of the optical disc in ways that make it difficult to both write and read. Still other schemes rely on network connections or secondary “key” disc schemes that do not allow stand-alone protection.
Horstmann (U.S. Pat. No. 6,044,469) discloses a software protection mechanism with a Protector Module that reads a license file and executes code based upon the license that has been purchased. Thus, it protects software at the logical level, especially for parts of the software for which rights have not been granted. If this system were included on a compact disc, a reproduction of this disc using a standard CD writer would make a copy with all the existing access in place.
Asai et al (U.S. Re. 35,839) describes a method of using an identifier region on a compact disc to store data that is compared with data stored elsewhere on the disc to verify authenticity. While this protects the data on a logical level, a simple bit-for-bit copy of the disc would subvert this protection scheme.
DeMont (U.S. Pat. No. 5,982,889) teaches a method for verifying the authenticity of a user's access to information products. The disadvantage of this system is that authentication is done via a central site. The user who does not wish to (or cannot) connect to the network is excluded from using this product.
Hasebe, et al (U.S. Pat. No. 5,555,304) describe a system, which is keyed to the individual user and to computer used. This limits an authorized user to the use of the program on a single computer, and severely restricts the users' mobility or ability to upgrade their equipment. Further, while this patent also claims the use of data stored in an un-rewritable area of a disc, the manner in which it is made un-rewritable leaves open the possibility of copying the data (including the “unrewritable” portion) to a fresh disc.
A series of patents by Fite et al (U.S. Pat. Nos. 5,400,319, 5,513,169, 5,541,904, 5,805,549, and 5,930,215) discloses a method of creating a machine-readable serial number code on optical discs by selectively removing the reflective layer from small areas of the disc in a way that creates a definable code. The disadvantage to such a system is that special equipment is required to write this special code.
Kanamaru (U.S. Pat. No. 5,940,505) teaches how a CD-ROM may be copy-protected. However, all embodiments of Kanamaru's invention require auxiliary hardware, either in the form of an integrated circuit or an additional computer board, to decrypt the information on the disc.
O'Connor et al., U.S. Pat. No. 5,745,568 discloses a method and system for securing CD-ROM data for retrieval by a specified computer system. A region of an optical disc is encrypted with a hardware identifier as an encryption key. The hardware identifier is associated to the selected computer hardware. The software program files contained in the CD-ROM are encrypted therein using the hardware identifier as an encryption key. The selected software programs on the CD-ROM are installed on the selected computer by decrypting the software program files using the hardware identifier as an encryption key.
Akiyama et al., U.S. Pat. No. 5,805,699, propose a software copying system which enables copyrighted software recorded in a master storage medium to be copied to a user's target storage medium in a legitimate manner. The master storage medium (i.e., CD-ROM) has a software identifier, and the target storage medium has a storage medium identifier. The two identifiers are sent to a central site, which manages licensing for the rights to copy software products. At the central site, a first signature is generated from the two identifiers which is sent back to the computer user. In the computer of the user a second signature is generated from the same two identifiers. Only when the two signatures coincide with each other can the software programs be copied from the master storage medium to the target storage medium.
Chandra et al., U.S. Pat. No. 4,644,493 discloses a method and apparatus which restricts software distribution used on magnetic media to use on a single computer. The original software contained on the magnetic medium is functionally uncopyable until it is modified by the execution of a program stored in a tamper-proof co-processor, which forms a part of the computer.
Indeck et al., U.S. Pat. No. 5,740,244 discloses an implementation by which a software product on a magnetic medium may first instruct a computer in which it is inserted to read a fingerprint of a specified portion of the product and to compare this fingerprint with a pre-recorded version of the same fingerprint. If the fingerprints match, then the software product may permit the computer to further read and implement the application software stored thereon.
There are various problems associated with these methods. One is that many of them are open to what are known as “hacks,” which means that if one user determines the method of decrypting or using the application, it is very easy for that person to disseminate the manner of gaining access to the application. Some methods prevent this problem by making the use of a particular application dependent upon a particular hardware combination. This approach creates a problem of portability. The legitimate user cannot use the application on a computer in a different location. The application may fail to start if users change their hardware configuration, such as by an upgrade.